TWI648846B - Light detector - Google Patents

Abstract

A light detector includes an array of sensing elements, a plurality of scintillator units, and a reflective layer. The sensing element array is located on a substrate, and the sensing element array includes a plurality of sensing units. The scintillator units are located on the sensing element array, wherein the scintillator units are separated from each other and correspond to the sensing units. The reflective layer covers the scintillator unit, and the reflective layer is electrically connected to the sensing unit. At least one scintillator unit includes a plurality of scintillator particles, wherein each scintillator particle includes a scintillator particle core and a transparent conductive layer covering a surface of the scintillator particle core, and the scintillator particles are electrically connected to each other.

Description

Photodetector

The invention relates to a detector, and in particular to a light detector.

X-ray imaging is one of the important tools for medical diagnosis. At present, X-ray imaging technology requires an X-ray detector that can absorb light energy and convert it into an electronic signal. The X-ray detector usually includes a scintillator that can convert X-rays into visible light. Generally speaking, an X-ray detector is formed by aligning and bonding a scintillator film layer and a sensing array through an adhesive layer. However, the material and thickness of the adhesive layer will cause the visible light to be easily transferred. Scattering results in severe optical crosstalk, which reduces the resolution of the image. Therefore, how to make the photodetector have a good image resolution is really one of the problems that researchers currently want to solve.

The invention provides a light detector with good image resolution.

The invention provides a light detector, which includes an array of sensing elements, a plurality of scintillator units, and a reflective layer. The sensing element array is located on a substrate, and the sensing element array includes a plurality of sensing units. The scintillator units are located on the sensing element array, wherein the scintillator units are separated from each other and correspond to the sensing units. The reflective layer covers the scintillator unit, and the reflective layer is electrically connected to the sensing unit. The scintillator unit includes a plurality of scintillator particles, where each scintillator particle includes a scintillator particle core and a transparent conductive layer covering a surface of the scintillator particle core, and the scintillator particles are electrically connected to each other.

Based on the above, in the photodetector of the present invention, the reflective layer covers the scintillator unit and each scintillator unit includes a plurality of scintillator particles, so that the visible light generated after the scintillator particles are excited by light of a specific wavelength is concentrated. In the corresponding sensing unit, the image resolution is further improved. In addition, the surface of each scintillator particle core is covered with a transparent conductive layer; the scintillator particles are electrically connected to each other, so that the reflective layer can be electrically connected to the sensing unit, which can reduce light scattering and improve image resolution. .

In order to make the above features and advantages of the present invention more comprehensible, embodiments are hereinafter described in detail with reference to the accompanying drawings.

Hereinafter, the present invention will be explained more fully with reference to the drawings of this embodiment. However, the present invention may be embodied in various forms and should not be limited to the embodiments described herein. The thicknesses of layers and regions in the drawings are exaggerated for clarity. The same or similar reference numbers indicate the same or similar elements, and the following paragraphs will not repeat them one by one. In addition, the directional terms mentioned in the embodiments, such as: up, down, left, right, front, or rear, are only directions referring to the attached drawings. Therefore, the directional terms used are used to illustrate and not to limit the present invention.

FIG. 1 is a schematic top view of a light detector according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view taken along line A-A 'in Fig. 1. 3 is a schematic cross-sectional view of a photodetector according to another embodiment of the present invention.

1 and FIG. 2, the photodetector 100 includes a sensing element array 110, a plurality of scintillator units 120, and a reflective layer 130. In this embodiment, the light detector 100 is, for example, an X-ray detector.

The sensing element array 110 is located on the substrate 102. The sensing element array 110 includes a plurality of sensing units 115. The sensing unit 115 is configured to receive light in a specific wavelength range (for example, light in a wavelength range of 400 nm to 800 nm). In this embodiment, the sensing unit 115 is, for example, a PIN diode (P-intrinsic-N diode), but the present invention is not limited thereto, and the sensing unit 115 may also be another suitable photodiode. The substrate 102 may be glass, quartz, organic polymer, or an opaque / reflective material (eg, conductive material, metal, wafer, ceramic, or other applicable materials) or other applicable materials. If a conductive material or metal is used, an insulating layer (not shown) is covered on the substrate 102 to avoid short circuit problems. In some embodiments, the sensing element array 110 further includes a plurality of active element TFTs, a plurality of patterned electrodes 112, a passivation layer 114 and a planarization layer 116.

The active device TFT is located on the substrate 102 and is electrically connected to the corresponding sensing unit 115. The active device TFT can be a bottom gate thin film transistor or a top gate thin film transistor, which includes a gate G, a gate insulating layer GI, a channel layer CH, a source S, and a drain. Pole D.

For example, the active device TFT is a bottom-gate thin-film transistor. The gate G is located on the substrate 102, and the gate insulating layer GI covers the gate G. The material of the gate G may be a conductive material, such as a metal, a metal oxide, a metal nitride, a metal oxynitride, or a combination thereof. The material of the gate insulating layer GI may be an inorganic dielectric material, an organic dielectric material, or a combination thereof. For example, the inorganic material may be silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof; the organic material may be a polymer material such as a polyimide resin, an epoxy resin, or an acrylic resin.

The channel layer CH is located on the gate insulating layer GI, and the source S and the drain D are located on opposite ends of the channel layer CH, respectively. The material of the channel layer CH is, for example, amorphous silicon, microcrystalline silicon, single crystal silicon, organic semiconductor materials, oxide semiconductor materials, or other suitable materials. For example, the channel layer CH may include Indium-Gallium-Zinc Oxide (IGZO), zinc oxide (ZnO), tin oxide (SnO), indium-zinc oxide (IZO), gallium oxide Gallium-Zinc Oxide (GZO), Zinc-Tin Oxide (ZTO) or Indium-Tin Oxide (ITO). In some embodiments, opposite ends of the channel layer CH may contain dopants to form a source region (not shown) for connecting the source S and a drain region for connecting the drain D ( (Not shown). The material of the source S or the drain D may be a conductive material, such as a metal, a metal oxide, a metal nitride, a metal oxynitride, or a combination thereof.

The patterned electrode 112 is located between the corresponding sensing unit 115 and the substrate 102, and the active device TFT is connected to the corresponding sensing unit 115 through the patterned electrode 112. For example, as shown in FIG. 2, the patterned electrode 112 is in contact with the sensing unit 115 located thereon, and the drain electrode D in the active device TFT is coupled to the patterned electrode 112. In some embodiments, the patterned electrode 112 and the drain D or the source S are formed by the same patterned conductive layer. In some embodiments, the pattern of the patterned electrode 112 corresponds to the pattern of the sensing unit 115. The material of the patterned electrode 112 may be a conductive material, such as a metal, a metal oxide, a metal nitride, a metal oxynitride, or a combination thereof.

The passivation layer 114 covers the active device TFT and part of the patterned electrode 112. In some embodiments, the sensing unit 115 is located on the passivation layer 114 and is in contact with the patterned electrode 112 exposed by the passivation layer 114. The material of the passivation layer 114 may be an organic insulating material, an inorganic insulating material, or a combination thereof. The organic insulating material can be polyimide (PI), polyamic acid (PAA), polyamide (PA), polyvinyl alcohol (PVA), polyvinyl alcohol cinnamic acid Ester (polyvinyl cinnamate, PVCi), other suitable photoresist materials, or combinations thereof. The inorganic insulating material may be silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof.

The flat layer 116 covers the passivation layer 114 and the sensing unit 115, and the flat layer 116 has an opening 118 that exposes the sensing unit 115. The material of the flat layer 116 may be an organic insulating material, an inorganic insulating material, or a combination thereof. The organic insulating material may be PI, PAA, PA, PVA, PVCi, other suitable photoresist materials, or a combination thereof. The inorganic insulating material may be silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof. For example, the material of the flat layer 116 may be SU8 or a material for a black matrix.

At least one scintillator unit 120 is located on the sensing element array 110. The scintillator units 120 are separated from each other, and the scintillator unit 120 corresponds to the sensing unit 115. The scintillator unit 120 includes a plurality of scintillator particles 122. Each scintillator particle 122 includes a scintillator particle core 122a and a transparent conductive layer 122b covering a surface of the scintillator particle core 122a. In some embodiments, the scintillator particle core 122a emits visible light after being excited by a specific wavelength of light, which includes Gd ₂ O ₂ S: Tb, ZnS: Cu, ZnS: Ag, CaWO ₄ , GdOS: Tb, Y ₃ Al ₅ O ₁₂ : Ce (YAG: Ce), Gd ₂ SiO ₅ : Ce (GSO), Lu ₂ SiO ₅ : Ce (LSO) or BaFCl: Eu. In some embodiments, the scintillator unit 120 is in direct contact with the corresponding sensing unit 115. As shown in FIG. 2, the scintillator particles 122 are located in the opening 118 and are in direct contact with the sensing unit 115. In this way, there is no other film layer (such as a protective layer, a flat layer, or an adhesive layer) between the scintillator unit 120 and the sensing unit 115, so that the visible light generated by the scintillator particles 122 excited by light of a specific wavelength is concentrated on the corresponding The sensing unit 115 (that is, avoid visible light scattering generated by the scintillator particles 122), thereby improving the image resolution. In some embodiments, the method for forming the scintillator particles 122 in the opening 118 may be to first uniformly mix the scintillator particles 122, the solvent, and the additives to form a mixture. Then, the mixture is filled into the opening 118, and then the liquid is evaporated at a high temperature, so that the scintillator particles 122 are formed in the opening 118. In some embodiments, in addition to being located in the opening 118, the scintillator particles 122 may also be located on a flat layer 116 around the opening 118 (as shown in FIG. 2). The solvent includes water, isopropyl alcohol, or a combination thereof. The above-mentioned additives include a surfactant, a binder, or a combination thereof, wherein the surfactant includes a Surfynol series product, and the binder includes a polyvinyl alcohol (PVA), for example. . In some embodiments, the content of scintillator particles is about 4.5 wt% to 5.0 wt%, the content of water is about 45 wt% to 50 wt%; the content of isopropanol is about 40 wt% to 45 wt%; the interface The content of the active agent is about 1.5 wt%; the content of the binder is about 4.5 wt% to 5.0 wt%.

In addition, in order to improve the conductivity between the scintillator unit 120 and the sensing unit 115, in some embodiments, a conductive layer 140 may be further provided between the scintillator unit 120 and the sensing unit 115 (as shown in FIG. 3). The material of the conductive layer 140 may be a conductive material, such as a metal, a metal oxide, a metal nitride, a metal oxynitride, or a combination thereof.

The reflective layer 130 covers the scintillator unit 120, so that the visible light generated after the scintillator particle core 122a is excited by light of a specific wavelength will be confined in the corresponding sensing unit 115 by the reflective layer 130. In other words, the visible light converted by each scintillator unit 120 will be received by the corresponding sensing unit 115, thereby greatly improving the image resolution of the light detector 100. The material of the reflective layer 130 may be aluminum (Al), silver (Ag), chromium (Cr), copper (Cu), nickel (Ni), titanium (Ti), molybdenum (Mo), magnesium (Mg), and platinum (Pt ), Gold (Au), or a combination thereof, and the reflective layer 130 may have a single-layer, double-layer, or multilayer structure. For example, the reflective layer 130 may be a three-layer structure composed of Ti / Al / Ti or a three-layer structure composed of Mo / Al / Mo.

In addition, the reflective layer 130 is electrically connected to the sensing unit 115. In some embodiments, since each scintillator particle 122 includes a scintillator particle core 122a and a transparent conductive layer 122b covering the surface of the scintillator particle core 122a, and the scintillator particles 122 are in contact with each other, the scintillator particles can be made The 122 are electrically connected to each other, so that the reflective layer 130 can be electrically connected to the sensing unit 115 through the scintillator unit 120 (that is, the reflective layer 130 is electrically connected to the sensing unit 115 located below it through the vertical conduction). . In this way, a forward bias or a reverse bias can be applied to the sensing unit 115 by adjusting the voltage between the reflective layer 130 and the patterned electrode 112. That is, in some embodiments, the reflective layer 130 may be used as a common electrode. The material of the transparent conductive layer 122b may be a transparent conductive material, such as a metal oxide such as indium tin oxide, indium zinc oxide, aluminum tin oxide, aluminum zinc oxide, or indium germanium zinc oxide. In some embodiments, a transparent conductive layer 122b can be formed on the surface of the scintillator particle core 122a by a sol-gel (Sol-Gel) method. For example, a powder containing indium tin oxide (eg, 90 wt% indium oxide and 10 wt% tin oxide) can be uniformly suspended in the liquid by a dispersant, and then the scintillator particle core 122a is added. In the above liquid, a liquid thin film (having a thickness of about 1 μm) is formed on the surface of the scintillator particle core 122a by dip plating, and finally the liquid is evaporated by sintering to form a dense transparent conductive surface on the surface of the scintillator particle core 122a Layer 122b.

In the embodiment in which the reflective layer 130 is used as a common electrode, the reflective layer 130 may include a plurality of common electrode patterns 130 a (as shown in FIG. 1), and the common electrode patterns 130 a are separated from each other. In more detail, the common electrode patterns 130a are structurally separated from each other. In this embodiment, each common electrode pattern 130 a corresponds to the scintillator unit 120. In this way, since the scintillator particles 122 are in contact with each other and their surfaces are covered with the transparent conductive layer 122b, the sensing unit 115 can be electrically connected to the common electrode pattern 130a through the scintillator unit 120. In some embodiments, two adjacent common electrode patterns 130a are electrically connected to each other. For example, two adjacent common electrode patterns 130a can be electrically connected by a wire 130b. In this embodiment, the conductive line 130b may be a strip-shaped electrode located between two adjacent common electrode patterns 130a, but the present invention is not limited thereto. In other embodiments, the conductive line 130b may be other suitable patterns. In some embodiments, the common electrode pattern 130a and the conductive line 130b may be formed of the same patterned conductive layer. In addition, in some embodiments, the common electrode pattern 130a may also cover the active device TFT.

In some embodiments, the scintillator unit 120 'may further include a filling layer 124 located between each of the sensing units 115 and the reflection layer 130 (as shown in FIG. 3). That is, the filling layer 124 can fill the space in the opening 118 that is not filled by the scintillator particles 122 to improve the stability of the scintillator unit 120 '. In addition, the material of the filling layer 124 is, for example, an organic material, and in order to improve the conductivity between the reflective layer 130 and the sensing unit 115, in some embodiments, the material of the filling layer 124 may also be a conductive polymer, such as polypyrrole ( polypyrrole), polyaniline, or a combination thereof.

The sensing element array 110 may further include a plurality of scan lines SL and a plurality of data lines DL. In this embodiment, the plurality of data lines DL and the plurality of scanning lines SL intersect. In other words, the extending direction of the data line DL is not parallel to the extending direction of the scanning line SL. In addition, the scan lines SL and the data lines DL are electrically connected to the active device TFT. For example, the scan line SL is electrically connected to the gate G of the active device TFT; and the data line DL is electrically connected to the source S of the active device TFT. In addition, in order to improve the conductivity between the data line DL and the source S, in some embodiments, the data line DL and the common electrode pattern 130a are formed by the same patterned conductive layer. That is, the data line DL is electrically connected to the source S of the active device TFT through a contact window via that passes through the flat layer 116 and the passivation layer 114. In other embodiments, the data line DL and the source S can also be formed by the same patterned conductive layer.

The cover layer 150 covers the reflective layer 130 and the flat layer 116. In other words, the covering layer 150 covers the scintillator unit 120 and the sensing unit 115, so the scintillator unit 120 and the sensing unit 115 can be protected to prevent water vapor and oxygen in the environment from reacting with it, thereby effectively extending the photodetector. 100 years of life. In this embodiment, the cover layer 150 is a flexible cover layer, and the material thereof includes parylene, polydimethylsiloxane (PDMS), polyimide (PI), A polymer such as polyethylene terephthalate (PET), acrylic-based resin, or the same material as the passivation layer 114.

In summary, in the photodetector of the above embodiment, the reflective layer covers the scintillator unit and each scintillator unit includes a plurality of scintillator particles, so that the scintillator particles are generated after being excited by light of a specific wavelength. Visible light is concentrated in the corresponding sensing unit, thereby improving the image resolution. In addition, the surface of the scintillator particles is covered with a transparent conductive layer, and the scintillator particles are in contact with each other, so that the reflective layer can be electrically connected to the sensing unit, so that light scattering can be reduced, thereby improving image resolution.

Although the present invention has been disclosed as above with the examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field can make some modifications and retouching without departing from the spirit and scope of the present invention. The protection scope of the present invention shall be determined by the scope of the attached patent application.

100‧‧‧light detector

102‧‧‧ substrate

110‧‧‧ sensor array

112‧‧‧Patterned electrode

114‧‧‧ passivation layer

115‧‧‧Induction unit

116‧‧‧ flat layer

118‧‧‧ opening

120, 120’‧‧‧‧ scintillator unit

122‧‧‧ scintillator particles

122a‧‧‧Scintillator Particle Nuclei

122b‧‧‧ transparent conductive layer

124‧‧‧ Filler

130‧‧‧Reflective layer

130a‧‧‧Common electrode pattern

130b‧‧‧Wire

140‧‧‧conductor layer

150‧‧‧ overlay

via‧‧‧Contact window

TFT‧‧‧active element

G‧‧‧Gate

GI‧‧‧Gate insulation

CH‧‧‧ Channel layer

S‧‧‧Source

D‧‧‧ Drain

SL‧‧‧scan line

DL‧‧‧Data Line

FIG. 1 is a schematic top view of a light detector according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view taken along line A-A 'in Fig. 1. 3 is a schematic cross-sectional view of a photodetector according to another embodiment of the present invention.

Claims (8)

A photodetector includes: a sensor element array on a substrate, and the sensor element array includes a plurality of sensor units; a plurality of scintillator units on the sensor element array, wherein the scintillator units are connected to each other; Are separated from each other and correspond to the sensing units; a reflective layer covering the scintillator units, and the reflective layer is electrically connected to the sensing units; and a plurality of active elements are electrically connected to the corresponding ones, respectively. The sensing unit, and the reflective layer covers the active elements, wherein at least one scintillator unit includes a plurality of scintillator particles, each of the scintillator particles includes a scintillator particle core and covers the scintillator particle core A transparent conductive layer on the surface, and the scintillator particles are electrically connected to each other. The photodetector according to item 1 of the scope of patent application, wherein the reflective layer is electrically connected to the sensing units through the scintillator units. The photodetector according to item 1 of the scope of patent application, wherein the scintillator particle cores include Gd ₂ O ₂ S: Tb, ZnS: Cu, ZnS: Ag, CaWO ₄ , GdOS: Tb, Y ₃ Al ₅ O ₁₂ : Ce, Gd ₂ SiO ₅ : Ce, Lu ₂ SiO ₅ : Ce, or BaFCl: Eu. The photodetector according to item 1 of the scope of patent application, wherein each of the scintillator units further includes: a filling layer located between the corresponding sensing unit and the reflective layer. The photodetector according to item 1 of the scope of patent application, wherein each of the scintillator units is in direct contact with the corresponding sensing unit. The photodetector according to item 1 of the scope of patent application, wherein the reflective layer includes a plurality of common electrode patterns, the common electrode patterns are structurally separated from each other, and the common electrode patterns correspond to the scintillator units. And covering the active components. The photo detector according to item 6 of the patent application, wherein the two adjacent common electrode patterns are electrically connected to each other. The photodetector according to item 6 of the patent application scope, wherein the sensing element array further comprises: a plurality of scanning lines; and a plurality of data lines intersecting the scanning lines, wherein the scanning lines and the data The wires are electrically connected to the active devices, and the data lines and the common electrode patterns are formed by the same patterned conductive layer.